1. Field of the Invention
The present invention relates to protractors and chalk lines generally and, more particularly, but not by way of limitation, to a novel combination protractor/chalk line device.
2. Background Art
Both protractors and chalk lines are well known devices.
Protractors are of various types, but all are employed to measure angles, the simplest protractor being of planar form and having thereon an arcuate scale. An origin point on the protractor is placed at the intersection of two lines, for example, and the angle between the two lines is read from their positions relative to the scale.
Chalk lines are used to mark a straight line at a selected location on a substrate. Typically, a chalk line string is disposed in a housing in which a quantity of colored chalk is also disposed. As the chalk line string is withdrawn from the housing, it is coated with the colored chalk. The chalk line string is then placed tautly against the substrate and snapped against the substrate, thus marking the substrate with a colored line.
Known chalk line devices with or without measuring elements are as follows:
U.S. Pat. No. 997,803, issued Jul. 11, 1911, to Giffin, and titled CHALK LINE HOLDER, describes a combination chalk line and tape measure housing from which a chalk line and a tape measure may be selectively withdrawn. In one position of the housing, the line is chalked when it is withdrawn, while in another position, the line is withdrawn without being chalked. The only measurement function of the device is linear measurement with the tape measure.
U.S. Pat. No. 3,126,637, issued Mar. 31, 1964, to Short, and titled DUAL LINE CHALK BOX, describes a chalk line dispenser that has two chalk line reels disposed on a single shaft. The chalk lines are selectively used and, preferably, are coated with different colored chalks so that lines of different colors may be laid out by different tradesmen to reduce the possibility of confusion on a project. The device has no angle measurement function.
U.S. Pat. No. 4,731,933, issued Mar. 22, 1988, to Cope, and titled PROTRACTOR-CHALKLINE, describes a combination chalk line and protractor in which the chalk line itself is used as the protractor xe2x80x9cneedlexe2x80x9d after the chalk line is withdrawn past a scale of angles. A disadvantage of the device is that the housing thereof must be placed against a surface and cannot be freely held when an angle measurement is made.
U.S. Pat. No. 5,138,771, issued Aug. 18, 1992, to Lee, and titled THREE DIMENSIONAL HOMOLOGOUS SURVEYING INSTRUMENT, describes a surveying device which is related to the present invention in that it employs a pendulum device.
Accordingly, it is a principal object of the present invention to provide a combination protractor/chalk line device that includes both the function of angle measurement and the function of line marking.
It is a further object of the invention to provide such a combination protractor/chalk line device that is economically constructed.
It is an additional object of the invention to provide such a combination protractor/chalk line device that is easy to use.
It is another object of the invention to provide such a combination protractor/chalk line device in which the protractor function may be used while the device is freely held and contact with an element being measured is not required.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.
The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a combination protractor/chalk line device, comprising: a housing; a chalk line string disposed in said housing and withdrawable from said housing at a first end of said housing; manually graspable handle means loosely attached to said housing; a protractor disposed on a side of said housing; and said combination protractor/chalk line being arranged such that, when said chalk line string is withdrawn from said housing and held taut and said handle means is grasped, said protractor will indicate an angle from horizontal defined by said chalk line string.